Vent housing for advanced batteries

ABSTRACT

A system includes a vent housing configured to be installed on a lower housing of a battery module at a first side of the vent housing. The vent housing has a main body having an opening on a second side of the vent housing and an internal chamber coupled to the opening. The internal chamber includes a first wall having an internal burst vent configured to open at a first pressure threshold and a second wall having a ventilation vent comprising a gas-selective permeability layer.

BACKGROUND

The present disclosure relates generally to the field of batteries,battery modules, and battery housings. More specifically, the presentdisclosure relates to battery housings for battery modules that may beused in vehicular contexts, as well as other energy storage/expendingapplications.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A vehicle that uses one or more battery systems for providing all or aportion of the motive power for the vehicle can be referred to as anxEV, where the term “xEV” is defined herein to include all of thefollowing vehicles, or any variations or combinations thereof, that useelectric power for all or a portion of their vehicular motive force. Aswill be appreciated by those skilled in the art, hybrid electricvehicles (HEVs) combine an internal combustion engine propulsion systemand a battery-powered electric propulsion system, such as 48 volt (V) or130V systems. The term HEV may include any variation of a hybridelectric vehicle. For example, full hybrid systems (FHEVs) may providemotive and other electrical power to the vehicle using one or moreelectric motors, using only an internal combustion engine, or usingboth. In contrast, mild hybrid systems (MHEVs) disable the internalcombustion engine when the vehicle is idling and utilize a batterysystem to continue powering the air conditioning unit, radio, or otherelectronics, as well as to restart the engine when propulsion isdesired. The mild hybrid system may also apply some level of powerassist, during acceleration for example, to supplement the internalcombustion engine. Mild hybrids are typically 96V to 130V and recoverbraking energy through a belt or crank integrated starter generator.Further, a micro-hybrid electric vehicle (mHEV) also uses a “Stop-Start”system similar to the mild hybrids, but the micro-hybrid systems of amHEV may or may not supply power assist to the internal combustionengine and operates at a voltage below 60V. For the purposes of thepresent discussion, it should be noted that mHEVs typically do nottechnically use electric power provided directly to the crankshaft ortransmission for any portion of the motive force of the vehicle, but anmHEV may still be considered as an xEV since it does use electric powerto supplement a vehicle's power needs when the vehicle is idling withinternal combustion engine disabled and recovers braking energy throughan integrated starter generator. In addition, a plug-in electric vehicle(PEV) is any vehicle that can be charged from an external source ofelectricity, such as wall sockets, and the energy stored in therechargeable battery packs drives or contributes to drive the wheels.PEVs are a subcategory of electric vehicles that include all-electric orbattery electric vehicles (BEVs), plug-in hybrid electric vehicles(PHEVs), and electric vehicle conversions of hybrid electric vehiclesand conventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as comparedto more traditional gas-powered vehicles using only internal combustionengines and traditional electrical systems, which are typically 12Vsystems powered by a lead acid battery. For example, xEVs may producefewer undesirable emission products and may exhibit greater fuelefficiency as compared to traditional internal combustion vehicles and,in some cases, such xEVs may eliminate the use of gasoline entirely, asis the case of certain types of PHEVs.

As xEV technology continues to evolve, there is a need to provideimproved power sources (e.g., battery systems or modules) for suchvehicles. For example, it is desirable to increase the distance thatsuch vehicles may travel without the need to recharge the batteries.Additionally, it may also be desirable to improve the performance andreliability, and reduce the maintenance associated with such batteries.

One example of a battery module useful for the applications describedabove is one that includes multiple lithium ion electrochemical cellsand other features for managing the operation of the cells under variousconditions. Indeed, the ability of lithium ion electrochemical cells tobe charged faster and in a more reproducible manner than other batterytechnologies (e.g., lead-acid electrochemical cells, nickel-cadmiumelectrochemical cells) makes them particularly suited to address variouspower requirements of the applications noted above. In this regard, manyxEV applications include battery modules based on lithium iontechnology, either alone or in combinations with other energy storageand supply technologies (e.g., ultracapacitors, lead-acid batteries).

The lithium ion electrochemical cells generally include non-aqueousliquids (e.g., aprotic organic solvents) as their electrolyte liquids,for example due to the incompatibility of lithium metal with water. Inthis regard, each electrochemical cell will generally include its owncasing used to contain its specific components (e.g., electrodes,electrolyte fluids). Also, the lithium ion electrochemical cells and, insome instances, a housing of the battery modules containing these cells,may be hermetically sealed to limit exposure of the electrochemicalcells and their internal components to moisture.

During operation (e.g., charging and discharging), the lithium ionelectrochemical cells may become heated as a result of variouselectrochemical and thermodynamic processes occurring within the cells.This heat may cause the electrolyte liquids, among other things, toexpand and in some situations volatilize, which in turn raises theinternal pressure of the electrochemical cell and causes the individualcasing of the electrochemical cells to expand. Further, as the lithiumion electrochemical cells experience an increase in internal pressure,they may begin to vent certain gases. For example, vented gases mayinclude, but are not limited to, volatilized electrolyte.

For this reason, lithium ion electrochemical cells may be designed towithstand a certain amount of expansion, and may also include variousinterconnects or other features for venting gases into the batterymodule. Despite these approaches, in some instances, the degree ofheating, or some other force placed upon lithium ion electrochemicalcells, may be sufficient to cause one or more of the lithium ionelectrochemical cells to vent a relatively large volume of gases intothe housing of the battery module. To prevent rupture of the housing ofthe battery module, these gases may need to be vented as well.

Battery modules, therefore, may include a vent that is either connectedto a vent tube in a vehicle or is sealed with a valve, or both, whichenables the release of these gases from the battery module and into thevent tube of the vehicle or the ambient environment. However, it ispresently recognized that the vents associated with such modules may besubject to further improvement, for example if the housing of a batterymodule were to enable directional venting of the gases, and/or multipleventing operations.

SUMMARY

Certain embodiments commensurate in scope with the originally disclosedsubject matter are summarized below. These embodiments are not intendedto limit the scope of the disclosure, but rather these embodiments areintended only to provide a brief summary of certain disclosedembodiments. Indeed, the present disclosure may encompass a variety offorms that may be similar to or different from the embodiments set forthbelow.

The present disclosure relates to batteries and battery modules. Morespecifically, the present disclosure relates to housing for batterymodules. Particular embodiments are directed to lithium ion batterycells that may be used in vehicular contexts (e.g., xEVs) as well asother energy storage/expending applications (e.g., energy storage for anelectrical grid). Still more particularly, present embodiments relate toa housing for venting gases out of a battery module that includes, forexample, lithium ion electrochemical cells. For example, anelectrochemical cell may produce one or more gases that, through thenormal course of operation, are slowly released from the battery cell.Other times, the electrochemical cell may produce an excess of gasesthat are released much more quickly, and which must be directed out ofthe battery module. In such instances, a burst vent of a vent housingmay open to release and direct the excess gases away from the batterymodule, for example in a predetermined direction.

In an embodiment, a system includes a vent housing configured to beinstalled on a lower housing of a battery module at a first side of thevent housing. The vent housing has a main body having an opening on asecond side of the vent housing and an internal chamber coupled to theopening. The internal chamber includes a first wall having an internalburst vent configured to open at a first pressure threshold and a secondwall having a ventilation vent comprising a gas-selective permeabilitylayer.

In another embodiment, a system includes a lower housing sized to hold aplurality of lithium-ion electrochemical cells and having a firstconnection surface, and a vent housing configured to couple with thelower housing. The vent housing includes a main body having a secondconnection surface configured to mate with the first connection surface,an opening in a face of the main body, the face being oriented generallycrosswise relative to the second connection surface, and an internalchamber coupled to the opening and having an internal burst vent and aventilation vent. The ventilation vent comprises a gas-selectivepermeability layer.

In another embodiment, a system includes a lower housing holding aplurality of lithium-ion electrochemical cells, and a vent housingcoupled to the lower housing such that the cavity is sealed at aninternal pressure. The vent housing includes a main body having anopening on a face of the vent housing, and an internal chamber coupledto the opening. The internal chamber includes a first wall having aninternal burst vent configured to open when the internal pressure risesabove a first pressure threshold, and a second wall having a ventilationvent configured to enable gas exchange between the internal chamber andthe cavity.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective view of a vehicle (an xEV) having a batterysystem contributing all or a portion of the power for the vehicle, inaccordance with an embodiment of the present disclosure;

FIG. 2 is a cutaway schematic view of the xEV embodiment of FIG. 1 inthe form of a hybrid electric vehicle (HEV) having a battery module witha vent housing, in accordance with an embodiment of the presentdisclosure;

FIG. 3 is an exploded view of an embodiment of the battery module ofFIG. 2 having a base, a plurality of electrochemical cells, a housing,and a vent housing, the vent housing being configured in accordance withan embodiment of the present disclosure;

FIG. 4 is a perspective view of an embodiment of the vent housing ofFIG. 3, the vent housing having a hose connector on a face plate of thevent housing in accordance with an embodiment of the present disclosure;

FIG. 5 is an exploded view of the vent housing of FIG. 4 depicting themanner in which a face plate and the hose connector are arrangedrelative to a main body of the vent housing, in accordance with anembodiment of the present disclosure; and

FIG. 6 is an expanded partial view of an embodiment of an internalchamber of the vent housing of FIG. 5, the internal chamber having aninternal burst vent and a ventilation vent configured in accordance withan embodiment of the present disclosure.

DETAILED DESCRIPTION

It should be noted that terms such as “above”, “below”, “on top of”, and“beneath” may be used to indicate relative positions for elements (e.g.,stacked components of the power and battery assemblies described below)and are not limiting embodiments to either of a horizontal or verticalstack orientation. Further, should be noted that terms such as “above”,“below”, “proximate”, or “near” are intended to indicate the relativepositions of two layers in the stack that may or may not be in directcontact with one another. Additionally, geometric references are notintended to be strictly limiting. For example, use of the term“perpendicular” does not require an exact right angle, but defines arelationship that is substantially perpendicular, as would be understoodby one of ordinary skill in the art. Similarly, for example, the term“parallel” used in reference to geometric relationships does not requirea perfect mathematical relationship but indicates that certain featuresare generally extending in the same directions. Additionally, the term“planar” is used to describe features that are substantially flat, butdoes not require perfect mathematical planarity.

As set forth above, the battery systems described herein may be used toprovide power to a number of different types of xEVs as well as otherenergy storage applications (e.g., electrical grid power storagesystems). Such battery systems may include one or more battery modules,each battery module having a number of battery cells (e.g., lithium ionelectrochemical cells) arranged to provide particular voltages and/orcurrents useful to power, for example, one or more components of an xEV.As also described above, the various venting processes that may occur insuch a battery module may, in some situations, require relatively largevolumes of gases to be expelled from the battery module.

The present disclosure addresses these and other issues by providing,among other things, a vent housing for a battery module (e.g., a lithiumion battery module) that includes features configured to enable bothrapid venting of gases that may be produced by the electrochemical cellsas well as a relatively slower venting of other gases. By way ofnon-limiting example, the vent housing may correspond to an upper partof a battery module housing, and may be shaped and sized to mate with alower housing sized and shaped to contain a plurality of lithium ionelectrochemical cells. The vent housing may include, for example, one ormore burst vents, face plates, internal chambers, hose connections, andthe like, that enable both a rapid release of vent gases whenappropriate (e.g., when sufficient quantities of gas are released intothe battery module from the electrochemical cells), as well asdirectional venting of these gases in a predetermined direction. In thisway, the vent gases may be directed away from, for example, a passengercabin of a vehicle. The vent housing may also include one or moregas-selective permeability vents that are configured to enable a slowerrelease of certain vent gases, in essence allowing the battery moduleand its associated electrochemical cells to “breathe.” For example, thegas-selective permeability vents may enable gas exchange across amembrane, but do not allow moisture or condensation to pass through.

While it is envisioned that the embodiments noted above and described infurther detail below may be applied to any battery subject to venting asdescribed herein, the present approaches are particularly applicable tolithium ion battery modules that are subject to the variousenvironmental and operating conditions associated with, for example,driving a vehicle. With this in mind, FIG. 1 is a perspective view of anembodiment of an xEV 10 in the form of an automobile (e.g., a car)having a battery system 20, where the battery system 20 may provide allor a portion of the power (e.g., electrical power and/or motive power)for the vehicle 10, as described above. As described in more detailbelow, the battery system 20 may include one or more battery moduleseach having a vent housing that employs one or more vents to releasegases produced during operation or charging of the battery system 20.

Further, although the xEV 10 is illustrated as a car in FIG. 1, the typeof vehicle may differ in other embodiments, all of which are intended tofall within the scope of the present disclosure. For example, the xEV 10may be representative of a vehicle including a truck, bus, industrialvehicle, motorcycle, recreational vehicle, boat, or any other type ofvehicle that may benefit from the use of electric power. Additionally,while the battery system 20 is illustrated in FIG. 1 as being positionedin the trunk or rear of the vehicle, according to other embodiments, thelocation of the battery system 20 may differ. For example, the positionof the battery system 20 may be selected based on the available spacewithin a vehicle, the desired weight balance of the vehicle, thelocation of other components used with the battery system 20 (e.g.,battery management systems, vents or cooling devices, etc.), and avariety of other considerations. Indeed, it is now recognized that nomatter where the battery system 20 is positioned, it may be desirablefor the vent housings as described herein to directionally vent gasesaway from the passenger area of the xEV 10. However, it is alsorecognized that non-directional venting may also be appropriate incertain circumstances.

Certain features of the battery system 20 and associated components maybe further appreciated with reference to FIG. 2, which illustrates acutaway schematic view of an embodiment of the xEV 10 in the form of anHEV having the battery system 20. The illustrated battery system 20includes a plurality of battery modules 22, though there may be only onebattery module 22 in other embodiments. In particular, the batterysystem 20 illustrated in FIG. 2 is disposed toward the rear of thevehicle 10 proximate a fuel tank 12. In other embodiments, the batterysystem 20 may be provided immediately adjacent the fuel tank 12,provided in a separate compartment in the rear of the vehicle 10 (e.g.,a trunk), or provided in another suitable location in the xEV 10. As maybe appreciated, it may be desirable to vent gases away from any one or acombination of these vehicle features, as well. Further, as illustratedin FIG. 2, an internal combustion engine 14 may be provided for timeswhen the xEV 10 utilizes gasoline power to propel the vehicle 10. Thevehicle 10 also includes an electric motor 16, a power split device 17,and a generator 18 as part of the drive system.

The one or more battery modules 22 of the battery system 20 may eachinclude a plurality of battery cells (e.g., lithium ion electrochemicalcells), which may be subject to the venting processes described above.Further, the battery system 20 may include features or components forconnecting the multiple battery modules 22 to each other and/or to othercomponents of the vehicle electrical system. For example, the batterysystem 20 may include features that are responsible for monitoring andcontrolling the electrical and thermal performance of the one or morebattery modules 22 and its associated electrochemical cells.

As discussed herein, the battery modules 22 of FIGS. 1 and 2 may eachinclude a respective vent housing 40 configured to enable directionalventing of gases, though it is presently contemplated that multiplebattery modules 22 (e.g., some or all) may be positioned in anadditional housing having the vent housing 40, or some other arrangementwhere the features described below are incorporated into a modulehousing or another housing. FIG. 3 depicts an embodiment of the mannerin which the vent housing 40 may be positioned relative to othercomponents of a single battery module 22. However, it should be notedthat the exploded perspective view in FIG. 3 is provided as an exampleto facilitate discussion of certain aspects of the vent housing 40, andis not intended to exclude the presence of other battery module features(e.g., a battery control module, service disconnects, terminals, andvarious thermal management features).

The battery module 22, as shown, includes a plurality of electrochemicalcells 42 (e.g., lithium ion electrochemical cells) each having arespective vent 43 to enable a release of gases when an internalpressure of the respective electrochemical cell reaches a certainthreshold. The illustrated battery module 22 also includes a batteryhousing 44 (e.g., a lower housing), and a base 46. While shown asseparate components, in certain embodiments, the battery housing 44 andthe base 46 may be integrally formed (e.g., molded, welded, fabricated)into a single piece into which the electrochemical cells 42 are placed.The battery housing 44 and the base 46 may therefore define a cavity 47for holding the electrochemical cells 42. The battery housing 44, ingeneral, protects the electrochemical cells 42 from the externalenvironment, may maintain the position of each electrochemical cell 42relative to the other electrochemical cells 42, and the cavity 47 maydefine a volume into which the electrochemical cells 42 vent theirgases.

To enable the electrochemical cells 42 to be substantially isolated fromthe environment external to the battery housing 44 (e.g., hermeticallysealed), the vent housing 40 may include a first connection surface 48that substantially matches a shape and size of a corresponding secondconnection surface 50 of the battery housing 44 (the lower housing).When placed in abutment, the battery housing 44 and the vent housing 40may be welded or otherwise sealed together, either in addition to or asan alternative to other fastening methods, which may substantially sealthe cavity 47.

As may be appreciated, the particular method used to seal the batteryhousing 44 and the vent housing 40 may depend on their materialconstruction. For example, the vent housing 40 and the battery housing44 may be partially or totally formed from any appropriate housingmaterial, such as sheet metal, plastic, or the like. Indeed, while thepresent approaches may benefit from the vent housing 40 and the batteryhousing 44 both being formed from sheet metal, for example due to arelatively higher strength and lower gas permeability compared to mostplastic materials, it is presently contemplated that a combination ofmaterials may be used. For instance, the first and second connectionsurfaces 48, 50 may be formed from a different material than other partsof the vent housing 40 and the battery housing 44, respectively,depending on the particular method desired for forming a seal betweenthe two. Furthermore, in certain embodiments, the first connectionsurface 48 and/or the second connation surface 50 may include a gasketor similar feature to enable the first and second connection surfaces48, 50 to be securely fit to one another before an additional sealingoperation.

In this regard, the particular size and shape of the vent housing 40,and at least the first connection surface 48, may vary depending on theparticular shape and size of the battery housing 44, where the shape andsize of the battery housing 44 is generally determined based on theshape, size, arrangement, and number of electrochemical cells 42 andother battery management features. Further, the battery housing 44 mayhave a similar geometrical arrangement to that shown for the venthousing 40, where the first connection surface 48 is defined by a lipextending around the entire perimeter of the vent housing 40 on a sidewhere the vent housing 40 meets the battery housing 44 (i.e., the lowerhousing). In other embodiments, the size of the battery housing 44 maybe bigger or smaller than the connection surface 50. In other words, theconnection surface 50 may be a different size than the rest of thebattery housing 44, so that the connection surface 48 of the venthousing 40 matches the connection surface 50 of the battery housing 44to form a tight seal.

As an example operation to connect these components, the electrochemicalcells 42 may be positioned within the battery housing 44, and the venthousing 40 may be placed above the battery housing 44 such that thefirst connection surface 48 and the second connection surface 50 aresubstantially matched in position. The first and second connectionsurfaces 48, 50 may then be welded together, brazed together,ultrasonically welded together, adhesively sealed together, and soforth. In certain embodiments, the resulting battery module 22 may bepurged of ambient air using an inert gas such as helium or nitrogen, orany other sufficiently unreactive gas, such that the cavity 47 is filledwith the gas at an internal pressure. Accordingly, when theelectrochemical cells 42 vent gases out of their respective vents 43,the internal pressure of the battery module 22 increases. As describedbelow with respect to FIGS. 3-6, the vent housing 40 includes a numberof venting features to resist rupturing the battery module 22 as aresult of this increase in internal pressure.

In addition to, or as an alternative to, forming a seal between the venthousing 40 and the battery housing 44, the vent housing 40 may beattached to the battery housing 44 using fasteners 52 such as clips,screws, bolts, pins, ties, and the like. The vent housing 40 and thebattery housing 44 may therefore include corresponding openings or otherattachment points 54 (e.g., as shown with respect to the battery housing44), such as threaded openings for screws and/or bolts. In theillustrated embodiment, the fasteners 52 may secure the vent housing 40to the battery housing 44 at attachment points 52 by bolting or screwingthe fasteners 52 into the attachment points 54. The fasteners 52 and theattachment points 54 may be positioned at locations partially orentirely around respective perimeters 56, 58 of the first and secondconnection surfaces 48, 50. Thus, the fasteners 52 and the weld (orother appropriate attachment method) seal the vent housing 40 to thebattery housing 44 so that the inside of the battery module 22 issubstantially isolated from the environment (outside of the batterymodule 22), except for certain vent features of the vent housing 40 asexplained in detail below.

Certain of the venting features, for example those discussed withrespect to FIGS. 4-6, may be covered by a face plate 60. The face plate60 may be configured to, itself, serve as an undirected venting feature(i.e., for relatively non-directional venting). For example, the faceplate 60 may be secured (e.g., fastened) to the vent housing 40 in amanner that enables slow venting of gases and, in certain embodiments,enables the face plate 60 to serve as a vent. For instance, the faceplate 60 may cover an opening in a surface 61 of a main body 62 of thevent housing 40 (e.g., a surface oriented generally crosswise to thefirst connection surface 48), and may be secured to the surface 61 usinga retention force that enables the face plate 60 to allow the opening tobe partially exposed and enable vented gases to escape. For example, theface plate 60 may enable venting around its perimeter in anon-directionally controlled manner, such as between the features thatfasten the face plate 60 to the vent housing 40.

An example configuration of the face plate 60 and other various ventingfeatures of the vent housing 40 is shown in FIG. 4. In particular, FIG.4 depicts an embodiment of the vent housing 40 including the face plate60 secured to the main body 62, and a lip 64 having the first connectionsurface 48 and extending from the main body 62. As illustrated, the faceplate 60 is coupled to the vent housing 40 at a first face 66 (e.g.,having the surface 61) positioned, for example, at a longitudinal end 67of the vent housing 40. The first face 66 may, in certain embodiments,be on the same side of the vent housing 40 where various electricalconnection points for the xEV 10 (FIGS. 1 and 2) are positioned. Theelectrical connection points are not particularly limited, but mayinclude, for example, a first electrical connection point 68 and asecond electrical connection point 69, which may connect to a servicedisconnect of the battery module 22 (e.g., to disconnect theelectrochemical cells 42 from the xEV 10), a ground of the xEV 10,battery terminal connectors of the xEV 10, and so forth. While the faceplate 60 is illustrated as being connected to the vent housing 40 atonly one face, it should be noted that the vent housing 40 may, in otherembodiments, include multiple face plates secured to the vent housing40. In certain embodiments, the multiple face plates may be fastened atdifferent retention forces to the vent housing 40 to enable venting atincremented pressures. In other words, multiple face plates on the venthousing 40 may be provided to enable staged venting (e.g., if multipleelectrochemical cells begin to rupture). Again, the positioning of theface plate 60 may be chosen to direct vented gases in a predeterminedarea, such as away from the passenger cabin of the xEV 10 and othercertain components of the xEV 10, but in a non-directional manner out ofthe space between the vent housing 40 and the face plate 60.

The retention force of the face plate 60 to the first face 66 may be atleast partially determined by, for example, the type and number offasteners 70 used to secure the face plate to the first face 66. Thefasteners 70, as illustrated, are screws that screw directly into thefirst face 66 of the main body 62, and may be chosen based on theirdiameter, number and degree of turn, and so forth, depending on thedesired retention. The fasteners 70, in other embodiments, mayadditionally or alternatively include bolts, pins, nails, snaps, orother attachments.

As depicted, the face plate 60 may be attached to the first face 66 inan undirected manner that allows vented gases 71 to be released fromunsealed regions between the face plate 60 and the first face 66 (e.g.,spaces between the fasteners 70). In this regard, it is presentlycontemplated that the amount of separation between the face plate 60 andthe face 66 may be adjusted to regulate the amount of vented gases 71that escape. Further, releasing the vented gases 71 in this manner alsoenables the gases 71 to be vented in a certain area of the batterymodule 22.

While the face plate 60 illustrated in FIG. 3 is a flat, continuoussurface, and non-directionally vents gases, the embodiment of the faceplate 60 in FIG. 4 also includes a hose connection assembly 72. The hoseconnection assembly 72 is configured to directionally release the ventedgases 71 into a corresponding vent hose of a vehicle (e.g., the xEV 10of FIGS. 1 and 2) when the pressure inside the battery module 22 ishigher than a burst threshold of an internal burst vent (discussed infurther detail below) of the vent housing 40. Thus, the vent housing 40may include multiple gas-releasing features configured to directionallydischarge the vented gases 71 from the interior to the exterior of thebattery module 22. The directionality of venting via the hose connectionassembly 72 may be determined by the particular configuration of thehose connection assembly 72 and the connected hose.

For example, as shown in the exploded view of FIG. 5, which correspondsto the embodiment of the vent housing 40 of FIG. 4, the hose connectionassembly 72 includes a hose connector 82 disposed in the face plate 60.The hose connector 82 secures a hose to the hose connection assembly 72to direct the vented gases away from the battery module 22. The hoseconnection assembly 72 also includes a cover 80 that fits into the hoseconnector 82 to, for example, place the vent housing 40 in anappropriate state for shipping. As depicted, when the cover 80 isremoved from within the hose connector 82, the vented gases 71 are ableto escape the battery module 22 in a direction defined by an opening 84in the hose connector 82. However, to enable further directionalventing, in certain embodiments the hose connection assembly 72 enablesventing into a connected hose which may extend a distance away from thevent housing 40 and to a desired area for release of the vented gases.The hose connector 82 may connect to the hose, as may be appreciatedwith reference to the illustration, through an interference or frictionfit. In other embodiments, the hose connector 82 may include threaded orhook connection to further ensure a secure connection to the hose.

Returning again to the exploded view of FIG. 5, and moving from the hoseconnection assembly 72 toward the main body 64 of the vent housing 40,the illustrated embodiment also includes a gasket 86 placed between thefirst face 66 and the face plate 60. As may be appreciated, the gasket86 may be configured to provide a tighter seal between the face plate 60and the first face 66 of the vent housing 40, for example to restrictgas movement between the first face 66 and the face plate 60 insituations where directional venting is desired. The gasket 84 mayinclude or be formed entirely from any suitable gasket material, forexample an elastomeric material (e.g., rubber), a metallic material thatis more ductile compared to the vent housing 40, etc. On the other hand,in embodiments where non-directional venting from the face plate 60 isdesired, the gasket 84 may not be present.

With the face plate 60 apart from the first face 66 and the fasteners 70out of corresponding fastener seats 88, it can be seen in FIG. 5 thatthe vent housing 40 may include an internal chamber 90 coupled to anopening 92 in the first face 66. The internal chamber 90 may include, asillustrated, an internal burst vent 94 and a ventilation vent 96. Asalso shown, the ventilation vent 96 may include a covering 98, which isconfigured to serve as a gas-selective permeability layer to enable onlygases to pass therethrough. For example, the covering 98 may allowcertain gases to exit through the ventilation vent 96 while resistingthe ingress of moisture or other potentially damaging materials to enterthe battery module 22 (e.g., into cavity 47). The ventilation vent 96having the covering 98 may therefore enable gas exchange between theinternal chamber and the cavity 47 of the battery module 22, whilepreventing the cavity 47 from being exposed to moisture or other debris.The material may include, for example, expanded polytetrafluoroethylene(e-PTFE). As one example, the covering 98 may include a GORE® ventavailable from W. L. Gore & Associates, Inc. of Newark, Del.

The various features in the internal chamber 90 may be furtherappreciated with reference to FIG. 6, which shows the internal burstvent 94 and the ventilation vent 96 in greater detail. In theillustrated embodiment, the internal burst vent 94 includes an internalvalve 100 having a first valve portion 102 and a second valve portion104 connected to one another, and retained within the internal chamber90 by way of a seating 106 having corresponding first and second seatingportions 108, 110. As shown, the first and second portions 102, 104 areboth annular in shape, but differ in size. In this regard, the retentionforce of the first and second valve portions 102, 104 may be the same ordifferent, depending on their fits within their respective seatingportions 108, 110. In some embodiments, this may enable the first andsecond valve portions 102, 104 to enable staged release of the ventedgases 71 based on incremented pressure thresholds, in addition to anystaged venting resulting from partial and total dislodging of the valveportions from their respective seating portions. In one particularembodiment, the second valve portion 104 may be a retaining feature forthe internal burst vent 94, which prevents the burst vent 94 fromcompletely dislodging into, for example, a vent hose of the xEV 10. Inother words, during an event where the first valve portion 102 isdislodged from its respective seating portion 108, the second valveportion 104 may remain attached to the first valve portion 102 toprevent it from lodging into, for example, the hose connection assembly72.

In certain embodiments, for example, a rise in internal pressure of thebattery module 22 to a first threshold pressure may cause the firstvalve portion 102 to unseat from the first seating portion 108. Thesecond valve portion 104, on the other hand, may not unseat at thisfirst threshold pressure, thereby restricting the movement of the firstvalve portion 102 within the internal chamber 90. Further, additionalretention features may be positioned on an opposite side of theillustrated valve portions 102, 104 such that the valve portions includeflanges, protrusions, or the like, that resist their dislodgement fromtheir respective seating portions 108, 110.

While the internal burst vent 94 is illustrated as positioned on a firstwall 112 of the internal chamber 90, the ventilation vent 96 is locatedon a second wall 114 of the internal chamber 90 oriented crosswise tothe first. The ventilation vent 90 may include holes or openings 116,and the covering 98 disposed over the holes or openings 116. Normally,the holes or openings 116 would allow a non-selective exchange of gases,moisture, and so forth, between the internal chamber 90 and theelectrochemical cells 42. However, such exchange may be resisted orprevented by the covering 98, which includes gas-selective regions 118(e.g., windows) formed from a gas-selective permeability layer such ase-PTFE. The gas-selective regions 118 allow only certain gases to pass,and enable a small amount of venting from the internal components of thebattery module 22 resulting from, for example, heating and resultingpressure increases. It should be noted that the holes or openings 116may be sized to prevent objects from entering from the internal chamber90 and into an electrified region of the battery module 22, such as thecavity 47. For example, the holes or openings 116 may be betweenapproximately 0.1% and 50% of the size of the opening 84 of the hoseconnection assembly 72, or of the opening left by the first valveportion 102 of the internal burst vent 100.

In view of the foregoing, the operation of the battery module 22 havingthe vent housing 40 may enable a number of technical advantages. Forexample, the vent housing 40 may, in certain embodiments, enabledirectional and/or staged venting of the battery module 22 should one ormore of the electrochemical cells 42 rupture or otherwise release gases.In one embodiment of the manner in which the staged venting occurs, oneor more of the electrochemical cells 42 may vent causing an internalpressure of the battery module 22 to increase to a first pressure, inturn causing the internal burst vent 100 to open, either partially ortotally. Again, the total or partial opening may occur in stages, whichmay correspond to a first set of stages. Once the internal burst vent100 has opened, the hose connection assembly 72 disposed on the faceplate 60 may enable a directional release of the vent gases 71.Additionally, during normal operation of the battery module 22, theventilation vent 96 may enable the internal portion (e.g., cavity 47) ofthe battery module 22 to vent, for example sealing gases, resulting fromexpected heating of the electrochemical cells 42. In other words, thecavity 47 will generally be at a higher pressure than the environmentexternal to the battery module 22, and the ventilation vent 96 enablescertain gases to be released from the cavity 47, into the internalchamber 90, and, in certain embodiments, out of the internal chamber 90(e.g., between the face plate 60 and the first face 66 or out of thehose connection assembly 72).

While only certain features and embodiments of the invention have beenillustrated and described, many modifications and changes may occur tothose skilled in the art (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters (e.g., temperatures, pressures, etc.), mounting arrangements,use of materials, colors, orientations, etc.) without materiallydeparting from the novel teachings and advantages of the subject matterrecited in the claims. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. It is, therefore, to be understood that the appended claimsare intended to cover all such modifications and changes as fall withinthe true spirit of the invention. Furthermore, in an effort to provide aconcise description of the exemplary embodiments, all features of anactual implementation may not have been described (i.e., those unrelatedto the presently contemplated best mode of carrying out the invention,or those unrelated to enabling the claimed invention). It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerous implementationspecific decisions may be made. Such a development effort might becomplex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

1. A system, comprising: a vent housing configured to be installed on alower housing of a battery module at a first side of the vent housing,comprising: a main body having an opening on a second side of the venthousing; and an internal chamber coupled to the opening, comprising: afirst wall having an internal burst vent configured to open at a firstpressure threshold; and a second wall having a ventilation ventcomprising a gas-selective permeability layer.
 2. The system of claim 1,wherein the vent housing comprises a face plate coupled to a face of themain body and disposed over the opening.
 3. The system of claim 2,wherein the face plate comprises hose connector configured to enableconnection with a vent hose.
 4. The system of claim 3, wherein the hoseconnector is configured to direct gases from the internal chamber in aspecific direction through the face plate.
 5. The system of claim 3,wherein the hose connector comprises an annular insert in the faceplate.
 6. The system of claim 2, wherein the vent housing comprises agasket disposed between the face plate and the face of the vent housing,wherein the gasket is configured to restrict movement of gases passingbetween the face plate and the face of the vent housing.
 7. The systemof claim 1, wherein the internal burst vent comprises a valve seatdisposed in the first wall, and a valve retained within the valve seat,and the first amount is such that the valve remains partially retainedin the valve seat, and the second amount is such that the valve istotally dislodged from the valve seat.
 8. The system of claim 1, whereinthe ventilation vent comprises a covering having the gas-selectivepermeability layer.
 9. The system of claim 1, wherein the ventilationvent comprises openings in the second wall.
 10. A system, comprising: alower housing sized to hold a plurality of lithium-ion electrochemicalcells and having a first connection surface; and a vent housingconfigured to couple with the lower housing, comprising: a main bodyhaving a second connection surface configured to mate with the firstconnection surface; an opening in a face of the main body, the facebeing oriented generally crosswise relative to the second connectionsurface; and an internal chamber coupled to the opening and comprisingan internal burst vent and a ventilation vent, wherein the ventilationvent comprises a gas-selective permeability layer.
 11. The system ofclaim 10, wherein the internal burst vent is disposed on a first wall ofthe internal chamber, and the ventilation vent is disposed on a secondwall of the internal chamber, the first and second wall being coupled toone another and being oriented crosswise to one another.
 12. The systemof claim 10, wherein the first wall of the internal chamber is generallyparallel with the opening, and the internal burst vent comprises a valvedisposed in a seating, the valve being configured to displace from theseating in a direction from the first wall toward the opening at apressure threshold.
 13. The system of claim 12, wherein the internalchamber is sized to accommodate the valve displaced from the seating.14. The system of claim 12, wherein the valve comprises a first portionand a second portion disposed within a first seating portion and asecond seating portion, respectively, and wherein the first portion isconfigured to displace from a seating portion, and the second portion isconfigured to retain the first portion within the internal chamber afterthe first portion is displaced from the seating portion.
 15. The systemof claim 10, comprising a face plate secured to the face of the venthousing and over the opening.
 16. The system of claim 15, comprising ahose connection assembly disposed in the face plate, the hose connectionassembly comprising a hose connector secured to the face plate, whereinthe hose connector is configured to connect to a vent hose of a vehicle.17. The system of claim 10, wherein the lower housing, the vent housing,or a combination thereof, is made of sheet metal.
 18. The system ofclaim 17, comprising a gasket positioned on the first connectionsurface, the second connection surface, or a combination thereof. 19.The system of claim 17, wherein the first and second connection surfacescomprise corresponding threaded openings to enable them to be fastenedto one another.
 20. A system, comprising: a lower housing holding aplurality of lithium-ion electrochemical cells; and a vent housingcoupled to the lower housing such that the cavity is sealed at aninternal pressure, wherein the vent housing comprises: a main bodyhaving an opening on a face of the vent housing; and an internal chambercoupled to the opening, wherein the internal chamber comprises a firstwall having an internal burst vent configured to open when the internalpressure rises above a first pressure threshold, and a second wallhaving a ventilation vent configured to enable gas exchange between theinternal chamber and the cavity.
 21. The system of claim 20, wherein thevent housing is coupled to the lower housing with at least a weld. 22.The system of claim 21, wherein the vent housing is coupled to the lowerhousing with fasteners in addition to the weld.
 23. The system of claim20, wherein the vent housing comprises a face plate coupled to the faceof the main body and disposed over the opening, wherein the face platecomprises a hose connector configured to direct gases away from the venthousing when the internal pressure of the cavity rises above the firstpressure threshold.
 24. The system of claim 20, wherein the ventilationvent comprises a plurality of openings in the second wall, and acovering having a gas-selective permeability layer disposed over theplurality of openings, and wherein the ventilation vent is configured toresist ingress of moisture into the cavity through the plurality ofopenings.